In a semiconductor device manufacturing process, for example, an atomic Layer Deposition (ALD) is performed to form various films for forming an etching mask or the like, on a semiconductor wafer as a substrate (hereinafter, referred to as a “wafer”). In order to enhance the productivity of semiconductor devices, the ALD is sometimes performed by an apparatus that rotates a rotary table on which a plurality of wafers is mounted, while revolving the wafers, and repeatedly passes the wafers through a processing gas supply region (process region) defined along a diametric direction of the rotary table.
With the miniaturization of a wiring constituting a semiconductor device, it is sometimes requested to perform a film formation process at a high uniformity such that, for example, film thicknesses of respective portions in a surface of a wafer deviate within a range of 1% or less from a target value. In addition, with the miniaturization of the wiring, a loading effect within the surface of the wafer is relatively large during an etching process. As such, for example, there is sometimes a desire to form a film thickness distribution of a concentric circular shape in which, for example, a film thickness of the central portion of the wafer is larger than that of the peripheral portion of the wafer. That is to say, it is requested that the film formation process is performed at a high uniformity in the circumferential direction of the wafer.
In the film formation apparatus that revolves the wafers, however, because the processing gas is supplied along the diametric direction of the rotary table, the thickness distribution of a film formed on the respective wafer tends to vary from the central side of the rotary table toward the peripheral side of the rotary table. This makes it difficult to form a film thickness distribution having a high uniformity in the circumferential direction of the wafer. For example, there is known a film formation apparatus which forms a predetermined temperature distribution within a surface of a wafer, and performs a chemical vapor deposition (CVD), thus forming a film thickness distribution of a concentric circular shape as described above. However, in this film formation apparatus, the wafer is not revolved during the film formation process. As such, this apparatus fails to address the above problems.
In order to improve the uniformity of film thickness in a circumferential direction of a wafer, a film formation apparatus provided with the aforementioned rotary table is under consideration in which a rotating mechanism for rotating a mounting stand on which the wafer is mounted, in the circumferential direction, is installed in the rotary table. However, in the film formation apparatus configured as above, a load caused by a rotating mechanism is applied to the rotary table in addition to a centrifugal force caused by the rotation of the mounting stand. Therefore, in order to prevent a breakage of the rotary table, it is considered that the rotary table is required to be formed by a relatively strong material (e.g., a metal such as aluminum (Al)). When the rotary table is formed of the metal, it is necessary to perform a film formation process on the wafer at a relatively low temperature (e.g., a temperature of 200 degrees C. or less) in order to prevent deformation by heat. This makes it impossible to form desired kinds of films or a film having a desired film quality.